DENVER  Anthony Rizzo was born in Fort Lauderdale, raised just a few miles from the stadium that housed the favorite baseball team of his youth. It’s a ballpark that seemed to change its name just about every year the Florida Marlins have played there.

Things can change terribly fast in major league baseball, too, like the Padres’ decision to designate first baseman Jorge Cantu for assignment in the aftermath of a 6-3 loss to the Colorado Rockies on Wednesday at Coors Field. Though only 21 years old, Rizzo already understands the business of baseball and its cruelties and maybe even his role in the veteran’s departure, but he also still felt like a kid as he watched Cantu hug out his goodbyes with teammates.

“I grew up a Marlins fan and definitely followed Jorge with them (2008-10),” Rizzo said. “It was fun watching him with my team, and when I found out the Padres signed him (last winter,) I thought, ‘That’s awesome.’ ”

Rizzo’s new presence in the Padres clubhouse surely has much to do with Cantu’s absence, though the much-respected veteran admitted that he couldn’t snap out of a slump that had him batting .194. Cantu’s opportunities to play and bat weren’t going to increase, either, with the Padres intent on getting the celebrated Rizzo as much major league experience as possible.

“Oh man,” Cantu said. “Just watching Rizzo take his at-bats, he’s such a pro at such a young age. He takes balls that are close. He doesn’t swing at just any bad balls. He’s just a joy to watch. I was in his shoes just a few years ago. I’m happy to see kids like him have success.”

Given his own struggles in his first two games at Coors Field, Rizzo considered it a success to get a lone single in a game Wednesday that was entirely decided by an extraordinary string of one-base hits by the Rockies.

Clinching the three-game series, the Rockies countered a solo home run by San Diego’s Rob Johnson with six runs on 10 singles over the fifth and sixth innings, including nine base hits over a span of 10 at-bats. The damage was shared by starter Mat Latos — pulled with one out in the sixth and a 2-1 deficit to Rockies whiz Jhoulys Chacin — and reliever Chad Qualls.

“I threw the ball fine,” said Latos, tagged with four of the runs and a 4-8 record. “(Todd) Helton got a weak base hit. (Carlos) Gonzalez got a weak base hit. (Charlie) Blackmon, weak base hit. Looking back, honestly, only one ball was hit hard, and that was (Troy) Tulowitzki’s (second-inning) double.

“You know, that’s how baseball is. Helton hits a curveball maybe 100 feet. … Last time, Helton got me with a home run. This time, he got me with a … I don’t even know what I can say that was.”

The loss came at the end of a 20-game stretch without a break for the Padres, their longest of the season, which they split 10-10. But they lost six of their last eight and two of three at Colorado, where the Padres struck out 30 times over the series and continually stranded runners. An exception Wednesday was Chris Denorfia, who drove in the two Padres runs with singles.

After their first day off since May 26, the Padres return to interleague play Friday for the start of three games at Minnesota, then go to Fenway Park to play three against the Boston Red Sox. Expect to see more new faces around in the process.

While waiting to see if Cantu will be traded or waived, the Padres are believed to be contemplating a call-up of Triple-A Tucson corner infielder Jesus Guzman, a right-handed batter with a .332 average and .423 on-base percentage. (THURSDAY UPDATE: Guzman has been promoted.)

Since his own call-up last week, Rizzo has already experienced ups and downs, elation and exasperation. The latter were quite apparent in the Padres’ split of the first two games in Denver. Rizzo looked a bit discomfited in striking out thrice Tuesday, but with his line-drive solid single in the fifth inning Wednesday, he sounded highly encouraged for a rookie on a 1-for-15 stretch.

“I’m still trying to get everything back into check,” he said. “Today, I felt normal in the box again and taking good swings again. I’ve got to bring that every day. Personally, I made giant strides today.”

Cantu, a clubhouse favorite whose strong identity in Mexico made him even more attractive to the Padres as a free agent, had seen the writing on the wall with his .232 on-base percentage, .517 OPS, three homers and 16 RBI.

“I wasn’t surprised,” said the veteran of six-plus seasons. “This is how baseball goes. When people are high on you and you don’t respond well, this is what can happen. I understand. The opportunity (manager Bud Black) gave me, which I thank him for, I just couldn’t deliver.”